Automatic brake.



A. H. ALKIRE.

AUTOMATIC BRAKE. APPLICATION FILED FEB-8,19]?

Patentd June 5, 1917 I EJ675697 ALBERT H. ALKIRE, OF DES MOTNES, IOWA.

AUTOMATIC BRAKE.

Specification of Letters Patent.

Patented June 5, 1917.

continuation of application Serial iio. 132,189, filed November 18,1916. This application filed February 8,

To all whom it may concern.

Be it known that I, ALBERT H. ALKIRE,

a citizen of the United. States, and resident of Des' M0ines,-in thecounty of Polk and State of Iowa, have invented certain new and usefulImprovements in Automatic Brakes, of which the following is aspecification.

My invention relates generally to selfpropelled vehicles andspecifically to an automatically operating brake for preven'tmgaccidental retrograde movement of the ve-' hicle. I

This application is a. continuatlon ofmy application Serial No. 132,139,filed November 18, 1916.

It is well-known that means should be provided 'for' preventing backwardmovemerit of an automobile except as required by thev driger, and manydevices havingthat object in have been proposed. A fundamental'objcction to all thereof has been that ,the parts constitutingthe checking element'have been active during normal for ward movement ofthe vehicle. This resulted in wear and failure at the time when mostrequired.

An object in the present structure 1s to provide an automaticallyoperating clutch for preventing accidental backward movement, theoperative or movable parts of which are rigidly held in fixed position'during normal operation In the device as I propose to construct it theclutch elements are held out of contact by-utilizing a well knownmechanical principle, that of centrifugal force. Thus during normaloperation there is no actuation of the clutch element. 7 clutch parts isust at the instant of start ing and stopping. Thus the amount of wear oftheparts is negligible, particularly 1n view of the fact that the partsare -preferabl located within "he transmission case an operate in a bathof grea e or heavy oil. Oneof the important advantages of amonstructionsuch as described is its simplicity and-consequent 10w first cost. It 1sneedless to dwellupon these requisites to the adoption of any device asstandard equipment by automobile builders. as they are well known. Itmay be pointed out, however,

that the adaption of the device to a standard transmission mechanismwill. not complicate The only Jiiovement of any of the Serial No.147,383.

'stood by reference to the accompanying drawings, wherein,

Figure 1 is a plan view of an open trans mission case showing aconventional form of transmission mechanism, my invention being show-nin'conneotion' therewith;- Fig. 2 is a sectional view on the line 2---2of Fig. 1; F .ig.- 3 is a sectional. View on the line 33 of Fig. 2, and,Fig. 4c is a similar view showing the parts in the position. they willassume when the reverse gears are in mesh. In the drawings, the gearcase is 1nd1- eated at 10, and the transmission shaft at '11. This shaftis intermittently connected to the engine through a friction clutch,neither the engine nor the clutch being illustrated. The propeller shaft12, is connected to the driving wheels through the usual differcntial.The transn'iission mechanism includes a counter-shaft 13, having certaingears thereon, one'of which is intended to mesh witlrthe reverse gear14. This gear is shifted on the squared portion 15,, of the propellershaft by means of a yoke 16, which engages a hub 17, rigid with thegear. Secured to the propeller shaft 12, by means of a key 18, is astrongly built collar 19, having in this instance four longitudinal peripheral slots 20, therein. Pivoted at one end ofeach of said slots is apawl 2-1, both ends of which project outside of the limits of thecollar. The awls are pivoted at such point with such re ation to thelocation of the weight thereof that the heaviest end is at a pointfarthest removed from the reverse "gear 14:, with the object inflview'of causing the pawls to assume an extreme our-.- ward positionsuch as is shown-win Fig, 1,

whenever the propeller shaft is rotated. In

Fig. 4 the pawls are shown as forcibly held in outward position bycontact of the hub 17, of the re erse gear therewith. However, the pawls'wnl assume the same position when the propeller shaft is rotated ,venthough the reverse ge'ar'bein the ition of F1g. 1. When the propellershais idle,

however, the parts will assume the position shown in Fig. 3; that is,the two lower pawls will be in extended position while the two upperpawls will drop by gravity into such position as .to engage with theface 22, of a cam 23, rigidly secured to the wall of the transmissioncase 10. The arrangement is such that when the propeller shaft isrotated to the right, as viewed in Fig. 2, the pawls cannot engage theshoulder even though they are not held out of engagement by centrifugalforce. When, however, the propeller shaft stops even for an instant, oneof the four pawls will drop by gravity and prevent backward movement ofthe car.

If the driver wishes to run backward he will by means of his gear shiftlever move the reverse gear to the right, as viewed in Fig. 1, thuscausing the pawls to occupy the position of Fig. 4.

By providing a plurality of pawls there is an assurance of operation ofat least one thereof, and furthermore, the weight is balanceduipon thepropeller shaft thereby avoiding unequal wear or pounding.

By mounting the pawls in long slots of the character shown and bylocating the colhr 19, close to the cam, the ends of the pawls are indirect shear and there is practically no bending tendency. This involvesthe use of comparatively light weight members. During normal operationthe pawls do not move at all; that is, so long as the propeller shaft isrotated the pawls are held in a fixed position by centrifugal force. Theonly movement of the pawls occurs when the car stops. Thus wear isnegligible.

Obviously the form of mounting of the pawls is immaterial it being onlynecessary that the weight thereof be so disposed as to cause the same toremain out of engagement with the cam by centrifugal force during normaloperation.

I claim:

1. In a device of the class described, the combination of a drivenshift, a stop in proximity thereto, a pawl-mounted on said shaft .on atransverse pivot and unbalanced with relation to said pivot, saidpawlbeing mounted in such relation to said stop as to engage the samewhenthe shaft is stopped andto be rigidly. held out of engagement bycentrifugal force when said shaft is rotated and means for retainingsaid pawl in an inoperative position to perm'itpf reverse rota tion ofsaid shaft, s ib flantially as d e scribed.

2. In a device 6i lessees despribed, the

combination of a pfopeller shaft, a cam ad? iacent thereto,a-longitudinally slotted colar mounted on the shaft, and a lever mountedin the slot, the heavy endof whichlever projects beyond the limits ofsaid collar and engages said cam when the parts are still,

and 1s eentrifugally maintained outof con tact with said cam when saidshaft is rotated, substantially as described.

3. In a safety brake, the combination of a shaft, a slotted collarthereon, an unbalanced pawl in said slot, a cam with which said pawl maycooperate to prevent accidental reverse rotation of said shaft and meansfor retaining said pawl in an inoperative position to permit of reverserotation of said shaft, substantially as described.

4.. In a safety brake, the combination of a shaft, a cam stop adjacentthereto, a pawl mounted on said shaft on a tangential pivot,

said pawl being unbalanced and the heavyend being adapted to contactsaid cam stop, and a stop carried by the shaft and opposed to said camstop and adapted to support the end of said pawl at a point close to itspoint of engagement with the cam stop, substantially as described.

5. In a safety'brake, the combination of a shaft, a cam stop adjacentthereto, a pawl mounted on said shaft on a tangential pivot, said pawlbeing unbalanced and. the heavy end being adapted to contact said camstop, a stop carried by the shaft and opposed to said cam stop andadapted to support the end of said. pawl at a point close to its pointof engagement with the cam stop, and means operative by the reversegears for positive] holding said pawl out of engagement with said camstop, substantially as described.

6. In an automobile brake, the combination with the transmission shaft,a 'pawl pivotally mounted thereon, and a ratchet tooth fixed in the pathof the pawl and having an abrupt face and an inclined face over whichlatter the pawl slides when the shaft is revolving in a direction tomove the machine forward, of means connected with the reverse lever forholding the pawl out of contact with said tooth, substantially as de- 7.In an automobile brake, the combination with the transmission shaft, apawl pivotally mounted thereon, and a ratchet toothfixed in the path ofthe pawl and having an abrupt face and an inclined face over whichlatter the pawl slides when the shaft is revolving in a direction tomove the machine .forward, of an element slidably mounted on the shaftand adapted in one position to hold the pawl out of contact with saidratchet tooth, and connections-between said element and the reverselever, for-the P pose set forth.

8. In an automobile bralie, the combination with the transmission shaft,a disk fixed thereon, a pawl pivotedin the edge of-the disk and havingone end heavy and theother end turned inward toward the shaft, and a:

adjacent said inturned end ofthe pawl, and

connections between this disk and the reverse out of Contact with lever,whereby movement (Hi-1511B lever slides ver Within reach the disk andthrows the heavy and of the tions between :3:

pawloutwm'd, for the purpose set forth; for tho purposo forth 9. In anautomobile brake, ti1e co1nbina Signed at Dallas Contain, 1mm this thirdtion with the transmission shaft, pawl fJiV day of February, 1917" iotally mountod thoreon, and an ratchet tooth (UK-Elfin? H A w fixed inthe path at the pawl aindilavlng an o abrupt face and 'an inclined,face, of an e10 Witnesses:

ment siidab] y mounted on the shaft and V 13mm" 1 1m 1w adapted in 011;;position to hold the pawl Lomfn f'l iiIilWllbIEWEh

